Oh that error. Yep, I had a transporter effect I created (nicked) for mission1, referenced it in mission2 by pointing to mission 1's folder. CRASH!
Copied it to mission 2's folder. No problemo.
Copy the file to sit next to your Mission XML.
"We should give him the send-off he deserves. He died saving us all. Prepare a Rocket-Shed for immediate launch."